In recent years, a mobile station represented by a PHS (Personal Handy phone Scheme), a portable phone, and the like, becomes popular, and as a result, it becomes possible to make a phone call or to obtain information regardless of place and time. In these days, in particularly, while the amount of information available keeps growing, a high speed and high quality wireless communication scheme capable of downloading of a large volume data is employed.
For example, as a next generation PHS communication standard capable of high speed digital communication, there are available ARIB (Association of Radio Industries and Businesses) STD-T95 (non-patent document 1) and PHS MoU (Memorandum of Understanding). In such communication, an OFDM (Orthogonal Frequency Division Multiplexing) system is employed. The OFDM is classified as a multiplexing scheme, or a scheme for effectively using a frequency band by partially overlapping carrier bands through use of many carriers on a unit time axis such that phases of signals to be modulated are orthogonal to each other between adjacent carriers.
Moreover, while a subchannel is allocated to each user in a time division manner according to the OFDM, there is available OFDMA (Orthogonal Frequency Division Multiplexing Access) according to which a plurality of users commonly use all subchannels and a subchannel with the best transmission efficiency for each user is allocated.
According to the ARIB STD-T95 and/or PHS MoU, a receiving device sends a modulation and coding scheme determined in adaptive modulation to a transmitting device via an anchor channel in the FM mode (fast access channel based on a map mode) (see, e.g., non-patent document 1) so that the transmitting device modulates data, using the MCS. With this arrangement, the transmitting device can communicate with the receiving device, using an MCS which is optimum in the communication environment at the time.
Further, as a technique for improving efficiency in using frequency resource in the whole wireless communication system by utilizing adaptive modulation, there is disclosed a technique for calculating the total traffic amount of the wireless communication system; determining a priority level in allocating radio resource to each terminal station, based on the calculated total traffic amount and the transmission speeds of respective terminal stations; and determining the amount of radio resource to allocate to the terminal station, based on the priority level (Patent Document 1).
Related Art Document
Non-Patent Document
    Non-Patent Document 1: ARIB (Association of Radio Industries and Businesses) STD-T95Patent Document    Patent Document 1: JP 2003-18647 A